Explosive device for use in fire fighting equipment systems and the like



June 19, 1951 A. MATHISEN 2,557,448

ExFLosIvE DEVICE FoE UsE 1N FIRE FIGHTING EQUIPMENT sYsTEMs AND THE LIKEFiled May 15, 1944 Patented `une 1.9, 1951 THE LIKE Anders Mathisep,Isleworth, England, assigner to Graviner Manufacturing Company Limited;Isleworth, Middlesex, England, a British corpo;

Application May 13, 1944, SerialNo. 535,508 In Great Britain May 3, 1943This invention relates to improvementsin explosive devices of the kindadapted to use in Afireghting equipment systems, fire-extinguishingapparatus,Y electrical switch devices and for similar purposes.-

Inorder to obtain actuation of apparatus parts and appliances infire-fighting systems and the like it has been proposed to use smallexplosive charges in the discharge heads of re extinguishers and thelike, and to ignite such charges by small electrically ignited fusescapable Aof energisationby closure of electrical switch de-Y vices suchas manually operated push button switches, llame or re detectingswitches, and crashor inertia andv gravity element opera-ted switchdevicesV and the like.

The object of the `present invention is to provide a compact explosivedevice capable of igni tion, preferably by electrical means but ifdesired also' by percussionv means, whereby a mechanism actuating orsecuring Amember is capable of dis placement by an explosive' charge toeffect required operation of apparatus, mechanical or electrical:devices andthe like,

To this end the present invention-consists in an explosive devicecomprising a tubular mem; ber to which a stud member is secured bymeansof a frangible rim, a4 closure member being adapted. to be insertedinto the tubular member to form an explosive substance4 containinglchamber between one end of said stud and said elosure member, meansbeing provided for igniting said explosive substance to displace thestud member.

The closure member may be provided witha longitudinal fine boreconduit,Y and an electricalltr energised fuse mounted for example in asuitable metallic fuse holder adapted to be securedinthe tubularmember,may be provided for ignitingf the said. explosive substancethrough the -conduit.

The closure member isV preferably provided withY a projection adapted toprotrude into saidl explosive substance,Y the ne bore conduit terminating in a y blind end in said projection, one or more ne holes beingproducedrtransversely in said projection sonas to` connect withAsaidconduit,.- ignition of the explosive substance beingeffectedthrougli saidconduit and hole or holes ina substantiallycentralposition inl the mass of explosive substance.

7 Claims". (c1. isi-fissi In one form of the invention-the niei'ribermay be provided witha restricted bore one end into which said studmember is adapted to fit,` a-thin rim being then provided upon memberwhich rim fit's inside the tubular member so as touabutdagainst the endo the restricted bore portion of the tubularV member:r d i In one formofthe invention, thea rim of the stud membernand the closure member mayAbe 16" spaced by a sleeve adapted to form the explosive containingchamberi and said sleeve and the clcsure membermay be screw-threaded soas to be secured together. I n this form of the inventid the lrim of thestud member may be `secured t6 said sleeve by soldering, brazing or thelillevso that these parts form anuexplosive containing chamber capableof insertion into the tubular member, in which they may be secured bythe rnetallic ignition deviceholde member,l which membermay serve tolock the parts irmly position.

`While the ignition means may be in any desiredform sulras a percussiondevice prefer4 ablyan electricallyignited fuse is secured in saidignition device holder;v said fuse comprising an electriccurrent-)heated element and van ightioncompoundsubstane adapted toignite said explosive substance tlrougli the said conduit and holes' inthe cl's'viire device.

The device of the present inventief; has` nuriferou's applications and ione form th tubular member s in the shape f' s cap de ice' adapted'to besecured in a; uidA cockY device bc the stud memberY bein'iadapted toengage a ccl shut-oiplgarrangd to close the said cock against iluid Howupon ig''iticn of said explosive substance- As the force which can beapplied to the thin rim o f meta-l upon the stud is` limited, thetubular member may be secured;- for exarfnple, in a hous-l ing, and thestudt may b e elongated ao. disposed transversely across a space in saidhousing inI which said transversely disposed stud mayV serve' as anabutment for an; actuating member ar'- ranged to, operate any type ofmechanism;` the4 4`5 force applied by said actuating member being;therefore taken by a thrustv at right anglesz to the axisof the studwhich does not apply force tubera. l., t,

In a, delay action electric switch device the tubular memberV may besecured to a fuse holder 3 containing a delay action fuse, the studmember engaging electric switch actuating mechanism adapted to operateelectric contacts upon ignition of said explosive substance at apredetermined time delay after electric ignition of said fuse.

The invention will now be described with reference to the accompanyingdrawings which show embodiments of the invention by way of example andin which:

Figure 1 shows a longitudinal vieW of the device with parts in section,

Fig. l-A shows a simplied construction omitting the retaining sleeve,

Fig. l-B is another view of the simplified construction of Fig. l-A,

Fig. 1-C is a longitudinal sectional View of the tubular member orcasing of the construction of Fig. 1, showing the terminal restrictedbore,

Figure 2 is an exploded view showing the unit of Fig. 1 with parts injuxtaposition,

Figure 3 shows a slightly modied form of the device shown in Figure 1applied to an appliance in the form of a liquid shut-01T cock,

Figure 4 shows another application of the device shown in Figure 1, thisbeing shown in normal unoperated position,

'Figure 5 is a similar view to Figure 4, shown in the operated positionand Figure 6 shows another modified form of device shown in Figure 1applied to an electric switch appliance.

Referring now to Figures 1 and 2, numeral 2 denotes a tubular memberhaving a teri minal restricted bore I2 to which the stud member 3 issecured by means of a frangible rim 4.

A closure member 5 is adapted to be inserted into member 2 to form achamber for containing explosive substance 6, and an electricallyignitable fuse I comprising electric current heated element 44 securedin a fuse holder 8 is screwed into member 2 to secure parts 3 and 5 inappropriate position in member 2 to form a chamber for explosive 6.

Closure member 5 is provided with a longitudinal fine bore conduit 9 asshown in Figure 1.

' As shown in the construction shown in Figure 1 and Figure 2, theclosure member 5 is provided with a projection I in which one or moretransverse ne bored holes II are provided the eiect of which is thatwhen fuse 'I is ignited, 4an ignition flame travels down conduit 9 andis deflected through holes II to ignite explosive substance 6practically in the center of said substance thereby increasing theexplosive effect. At the end of closure member which is oppositeprojection I0, ne bore conduit 9 terminates in a small conical recesswhich is adapted to receive fuse 'land conduct the ignition flametherefrom.

AOn occurrence of the explosion, the gaspressure passes back throughholes I I of which there may be one, two or four, these holes beingpreferably oppositely disposed so that the gas pressure streams strikein opposite directions into conduit 9 in which they are deflected atright angles back through conduit 9, the effect of which is to reduceloss of gas pressure and thereby risk of blow back.

In order that reliability of operation shall be obtained, it has beenfound necessary to make rim 4 approximately .018" thick if stud 3 is ofbrass.

- Conduit 9 may be of the order of .030 diameter whereas holes II aregenerally .015 diameter, the quantity of explosive substance beingbetween 3 to 5 grains of ne grain gunpowder.

In the simplied form of construction shown in Fig. l-A and Fig. l-Bwherein the explosive substance 5 is contained between the walls of thebore of tubular member 2 and stud 3 and closure member 5, and frangiblerim 4 of stud 3 is formed integrally in one piece with tubular member 2,there is risk during handling and assembly of fracturing rim 4, and forthat reason the more rugged construction shown in Figure 1 is preferredand in this form of Figure 1 the member 2 is provided with a restrictedbore I2 (Fig. 1-C) into which a portion of stud 3 fits reasonablytightly, rim 4 tting internally in sleeve 2 so as to retain stud 3therein.

As shown in the form of Fig. 1, rim 4 of stud 3 and closure member 5 maybe spaced from one another by a sleeve I3, this being adapted to fitinto member 2, a part of the closure member 5 and the sleeve I3 beingscrew-threaded so as to be secured together.

In this form employing sleeve I3, rim4issecured to sleeve I3 bysoldering, brazing or the like so that the parts 3, 4, 5 and I3 form achamber for containing explosive substance 6, the unit being capable ofinsertion into tubular member 2, in which it is secured by metallicholder 8 of fuse "I, so that when an explosion occurs, stud 3'will beblown out by theV explosive force, rim 4 being shorn off due to itscontact with the restrictedA the end of cap device 22 by a liquidexcluding washer I6.

Upon electrical ignition of fuse l', stud 3 will'be blown out and plugI5 blown across the cock body plug seating I'I where it is retained by acompression spring I8 which expands to retain plug I5 in the liquidshut-oir position.

Referring to the modification of Figs. 4, 5, a I

applied to an explosive releasable spring actuated control unit, sincethe force which can be applied to rim 4 is limited, the tubular member 2may be shaped in a modified form as shown at 23, Figures 4 and 5, inwhich case it can be secured in a housing I 9 which has a transverseportion or tube 20 integral therewith or secure thereto by welding asshown at 2|. -f'

Stud 33 (Figs. 4 and 5) is in this case elongatied compared to stud 3 ofthe form of Figs. 1-3, and is disposed transversely across the openspace in said housing, and a s-pring urged actuatingl member 24 isdisposed in the space in said housing portion or tube 20 to which it issecured by stud 33 which engages holes 25 in member 24.

By this means actuating member 24 can be displaced under action ofspring 26 when explosive material 6 blows stud 33, less rim 4, intocavity 2l in housing I9 as shown in Figure 5.

As will be seen, the thrust due to spring 26 is taken by stud 33 in atransverse direction-and is not applied to rim 4, and for this reasonconsiderably greater force can be applied to stud 33 than could beapplied longitudinally to stud 3, as there would be risk of shearing thethin rim 4 if excessive force is applied to the rim.

Referring now to the modiiication of Figure 6,

applied to an electric switch, stud 3 engages anv arm 28 hinged on pin29 which pin also supports a contact actuating member 30 which 'engagesamovable contact spring 3l adapted to opemor' close electric circuits bymeans .of spring contact points 32, one of which is secured to asemi-rigid spring contact 34.

As shown in Figure 6, contact points 32 are normally open and a tubularmember shaped as shown at 222 engages a metallic holder 35 whichencloses a delay action fuse 3S from which it is spaced by insulationsleeving 31. Y

In the particular construction Ashown in Figure 6, fuse 3S has a delayof ten seconds, 'thatis to say that when fuse 36is electricallyenergised it burns for ten seconds before explosive substance 6 isignited. By this means a time vla of the switch device is obtained.

-The explosive device and the Yswitch mechanism shown in Figure 6 isenclosed in metallic or plastic materia; casing 3.8@- which fuse holder35 is secured by bracket fand si'z'revvmeans 3 9, contacts 3l and 34being secured to lid 40 of casing 3'8 by securing bolts, insulationAsleeving -and spacers in known manner, electrical connections 4l beingtaken from contacts -3l and 34 to terminals 42 in an insulation terminalblock device 43 of known form.

Fuse 'l comprises yan electric current heated element 44, see Figure 2,which is connected to electric leads 45, which leads are connected toterminals 4S in a terminal block device 41 of known form.

For use in a, fire-fighting system upon aircraft, for example, theswitch device appliance shown in Figure 6 may be employed to introduce atime lag between the energization of fuse 36 due to operation of acontrol switch which is operated on occurrence of a fire and thedischarge of electrically energised fire-extinguishing appliances whichare controlled by closure of switch contacts 32.

In order to provide means for checking circuit continuity over contacts32, ian insulating cam 4S mounted upon spindle 49 is provided, said cambeing operable externally from the casing and being spring operated tobring this back into normal position as shown in Figure 6.

In order to permit escape of explosive gases from c-asing 38 when closedby lid 40, a disc 5D is pressed into a recess 5| in casing 38, whichdisc is struck by stud 3 upon ignition of explosive substance 6 todisplace the disc whereby the gases escape through an orice 52 in casing38.

As will be appreciated, the device of the invention constitutes a formof relay, in which a small electric current generally of the order of1/2 ampere is sufficient to eiect displacement or operation of la,mechanical device requiring considerable force, by use of a smallquantity of explosive substance.

By this means the appliance of the invention has considerable advantagesover electromagnetic relay and like devices which would require heavycurrents for effecting operation of mechanical appliances requiringcomparable force, and by this means a considerable reduction in Weightis obtained in appliances `as shown in Figures 3 to 6, which isimportant when these appliances are employed in fire ghting equipmentfor use upon aircraft.

Having thus fully described my invention, what I claim -as new anddesire to protect by Letters Patent is:

1. An explosive device comprising in combination a tubular member in theform of a cap device, a stud member secured to said tubular mem- 6 berby a frangible rim, a closuremember adapted to be inserted in saidtubular member, said tubular member defining an explosive substancecontaining chamber between one end of said stud and said closure member,means for igniting said explosive substance to displace said studmember, a fluid cock device body, means for securing said tubular memberin said body, a shut-off plug, means for securing said plug to said studmember, said fluid cock device body having a plug seating recess, andmeans for retaining said plug in said seating recess after displacementof said stud member by ignition of said explosive substance.

2. In an explosive actuatable valve comprising a valveseat and a bonnet,a plug, means in said bonnet for guiding' said plug into tightengagement with said valve seat, an explosive unit comprising a mountingterminal portion and a pro- `jectile terminal portion and a chambercontaining explosive material interposed between said terminal portions,said projectile terminal portion being rigidly mechanically connected tosaid chamber only by a frangible rim, said explosive unit furthercomprising means for igniting said explosive material, said mountingterminal portion being iixedly mounted in said bonnet, said projectileterminal portion being rigidly mechanically connected to said plug andbeing directed in the direction of the path of said plug to said valveseat, whereby ignition of said explosive material fractures saidfrangible rim and propels said plug along said guiding means into tightengagement withsaid valve seat.

3. A valve as set forth in claim 2, said bonnet further comprising ahelical spring mounted to urge said plug outwardly from said bonnet andupon projection of said projectile terminal portion to hold said plug intight engagement with said valve seat.

4. In anrexplosive actuatable valve comprising a valve seat and abonnet, a plug, means in said bonnet for guiding said plug into tightengagement with said valve seat, an explosive unit xedly mounted in saidbonnet and comprising a sleeve, a stud member comprising a frangible rimby which it is xedly attached to one end of said sleeve, a closuremember xedly attached to the other end of said sleeve, said sleeve andsaid stud member and said closure member dening an explosive chamber,explosive material in said chamber, said closure member comprising abore communicating with said chamber, a fuse mounted extending into saidbore, said bonnet comprising mounting means for xedly mounting said studmember and said sleeve and said closure member as a unit in said bonnet,said mounting means comprising a shoulder in engagement with saidfrangible rim, and a rigid direct mechanical connection between saidstud member and said plug, whereby ignition of said explosive materialfractures said frangible rim and propels said plug along said guidingmeans into tight engagement with said valve seat.

5. A valve as set forth in claim 4, said bonnet further comprising ahelical spring mounted to urge said plug outwardly from said bonnet andupon projection of said stud member to hold said plug in tightengagement with said valve seat.

6. An explosive actuatable valve as set forth in claim 2, saidprojectile terminal portion and its said frangible rim being formedintegrally with said chamber and said frangible rim constituting anintegral connection between said REFERENCES CITED The followingreferences are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 41,960 Graham Mar. 15, 186443,881 Graham Aug. 16, 1864 108,836 Schuler Nov. 1, 1870 387,651 MaximAug. 14, 1888 824,934 Jenczewsky July 3, 1906 Number 20 Number 8 NameDate Lewis Oct. 24, 1916 Lallman Sept. 25, 1917 Temple Jan. 18, 1921Medlin Dec. 27, 1927 Baumer Nov. 18, 1930 Driggs et al. Nov. 18, 1930Allen Oct. 18, 1932 Gillen June 13, 1933 Allen Dec. 18, 1934 Haines Nov.24, 1936 Mathisen et al Apr. 1, 1941 Alexander July 22, 1941 AlexanderJuly 22, 1941 Albree Nov. 25, 1941 Alexander Aug. 31, 1943 Turechek Aug.31, 1943 FOREIGN PATENTS Country Date Germany Apr. 22, 1920

